# std::ranges::join_with_view<V,Pattern>::iterator<Const>::operator++,--

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< cpp‎ | ranges‎ | join with view‎ | iterator

constexpr /*iterator*/& operator++(); | (1) | (since C++23)
constexpr void operator++( int ); | (2) | (since C++23)
constexpr /*iterator*/ operator++( int ) requires std::is_reference_v</*InnerBase*/> && ranges::forward_range</*Base*/> && ranges::forward_range</*InnerBase*/>; | (3) | (since C++23)
constexpr /*iterator*/& operator--() requires std::is_reference_v</*InnerBase*/> && ranges::bidirectional_range</*Base*/> && ranges::bidirectional_range</*InnerBase*/> && ranges::common_range</*InnerBase*/> && ranges::bidirectional_range</*PatternBase*/> && ranges::common_range</*PatternBase*/>; | (4) | (since C++23)
constexpr /*iterator*/ operator--( int ) requires std::is_reference_v</*InnerBase*/> && ranges::bidirectional_range</*Base*/> && ranges::bidirectional_range</*InnerBase*/> && ranges::common_range</*InnerBase*/> && ranges::bidirectional_range</*PatternBase*/> && ranges::common_range</*PatternBase*/>; | (5) | (since C++23)

Increments or decrements the iterator.

1) Increments the inner iterator as if by std::visit([](auto& it){ ++it; },`` `inner_it_`﻿);.
After that, adjusts the inner and outer iterators as follows:

- If the incremented inner iterator is the past-the-end iterator of the pattern range, it is set to an iterator to the beginning of the next inner range.
- If the incremented inner iterator is the past-the-end iterator of an inner range, the outer iterator is incremented. Then:

  - If the incremented outer iterator is not the past-the-end iterator of the outer range, the inner iterator is set to an iterator to the beginning of the pattern range.
  - Otherwise, if std::is_reference_v<`InnerBase`﻿﻿> is true, the inner iterator is set to a pattern iterator holding a singular value.

- Repeats the operations above until either the inner iterator is not a past-the-end iterator, or the outer iterator is a past-the-end iterator.

2) Equivalent to ++*this;.
3) Equivalent to auto tmp = *this;
++*this;
return tmp;.
4) If the outer iterator is the past-the-end iterator of the outer range, decrements it and sets the inner iterator to the past-the-end iterator of the last inner range, otherwise do nothing.
After that, adjusts the inner and outer iterators as follows:

- If the inner iterator refers to the beginning of an inner range, it is set to the past-the-end iterator of the pattern range.
- If the inner iterator refers to the beginning of the pattern range, the outer iterator is decremented, and the inner iterator is set to the past-the-end iterator of the previous inner range.
- Repeats the operations above until the inner iterator does not refer to the beginning of any range.

Finally, decrements the inner iterator as if by std::visit([](auto& it){ --it; },`` `inner_it_`﻿);.
5) Equivalent to auto tmp = *this;
--*this;
return tmp;.

### Return value

1,4) *this
3,5) A copy of *this that was made before the change.
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